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Old 10-04-2012, 09:08 AM   #19
Les Peterson
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Joined: Aug 2008
Location: Kennewick WA
Oddometer: 162
One of the biggest problems with this style of gasifacaiton is this method. To make this work a system will consume 40-60% of the feed material to make the syngas. This syngas is what is powering the mechanical process we see in these vidios. FYI the energy density for most "good" syngas systems is only about 320 BTU per cubic foot of syngas. Compare that to the BTU's of methane at 1013.2 and you get the picture. This pictured system is not a good syngas system, they are producing at least 40% CO2. Carbon dioxied in the combustion chamber is an energy robber, as in it takes heat away from combustion and when heating up displaces snygas and air. A person could help this some by using NOS or even liquid O2 if brave enough.
Someone mentioned that sulphur was a problem here. That is true to some extent but, the bigger problem is chloride compounds. All cellulosic material will have some chlorides in it along with the sulphur. This chloride is what produces the HCL or hydrogenchloride gas i.e. acid. Without a scrubber system installed then yes this causes major problems for the internal combustion engine, the piping, the compressor and whatever it touches.
I would love to see this technology more mobile but the engineering hurdles are huge. For instance, a 1megawatt sytem with all the EPA regulated items covered would require 7 semi trucks to move around. Not an option for the normal person.
Another way to gasify something would be to use the wood to fire a POX chamber. POX is partial oxidation where the oxygen and nitrogen is limited and controlled to optimize the production of syngas and minimize the production of CO2 and NOS compounds. If the POX reactor is kept hot enough (between 1100-1400 C) then the sulphur plates out on the walls and pipes as elemental sulphur and causes little harm. The HCL can be scrubbed with a simple sodium hydroxide liquid scrubber and kept at atmospheric pressure.
Maybe someday I will build me a syngas fired generator. A free fuel source would be required though as the cap cost to build something like this would be huge. A good blend of fuel would be to use wood, plastic (not PVC though) and shredded tires. Then I would install a waste heat recovery system to heat my home and shop and hot water. The syngas could also be used for cooking and firing the primary hot water heater and backup gas furnace for heating the house.
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